The effect of magnesium versus verapamil on supraventricular arrhythmias

Magnesium has previously been used in the treatment of various arrhythmias, but few randomized and prospective studies are available. In a single-blind study, the efficacy and safety of intravenous magnesium sulfate (bolus doses of 5 + 5 mmol followed by infusion of 0.04 mmol/min) versus verapamil (5 + 5 mg followed by 0.1 mg/min) was evaluated in 57 patients with supraventricular arrhythmias (supraventricular tachycardia, atrial fibrillation, and atrial flutter) of recent onset (less than 1 week). Fifteen (58%) of the patients receiving magnesium (n = 26) converted to sinus rhythm within 4 h, and 16 (62%) within 24 h. Verapamil caused a lower ventricular rate, but only six (19%) of the patients (n = 31) converted to sinus rhythm within 4 h (p < 0.01) and 16 (52%) within 24 h (NS). No side effects were observed during magnesium infusion, whereas six patients receiving verapamil had to be withdrawn from further study medication due to symptomatic side effects (hypotension in three, cardiac failure in three). Magnesium appears to be an effective and safe drug for the treatment of supraventricular arrhythmias. The overall efficacy for conversion to sinus rhythm is at least as effective as with verapamil, and its action is more rapid.     

Safe and effective conversion of persistent atrial fibrillation to sinus rhythm by intravenous AZD7009

BACKGROUND: Acute drug conversion of persistent atrial fibrillation usually fails. OBJECTIVES: The purpose of this study was to test the proarrhythmic potential, safety, and efficacy of the novel antiarrhythmic agent AZD7009 in patients with persistent atrial fibrillation (AF) or atrial flutter (mean duration 43 days) scheduled for direct current (DC) cardioversion. METHODS: Patients were randomized to AZD7009 (3-hour intravenous infusion; n = 86) or placebo (n = 36). AZD7009 was given in doses intended to produce target pseudo-steady-state plasma levels of 0.25, 0.50, 0.75, 1.0, 1.5, 2.0, or 2.5 micromol/L after 30 minutes of infusion. DC cardioversion was performed if conversion to sinus rhythm (SR) did not occur within 2 hours of infusion. RESULTS: AZD7009 in a concentration-dependent manner increased the rate of conversion of AF to SR and shortened the time to conversion. At the three highest target concentrations of AZD7009, 45%, 64%, and 70% of AF patients converted after a mean time of 62, 55, and 26 minutes, respectively, whereas no placebo-treated patients converted. SR was maintained for 24 hours in 21 of 22 patients with drug-associated conversion. AZD7009 treatment was associated with QT-interval prolongation; the increase in QT corrected according to Fridericia typically ranged from 40 to 80 ms at targeted pseudo-steady-state plasma concentrations >or=0.75 micromol/L, but a number of outliers with QT corrected according to Fridericia >550 ms were seen in the higher concentration groups, particularly after conversion to SR and prolonged infusion. None of the patients exhibited torsades de pointes according to predefined criteria; however, one patient exhibited a nonsustained, polymorphic ventricular tachycardia of eight beats with torsades de pointes-like features after AZD7009 infusion (asymptomatic and discovered only upon retrospective Holter tape analysis). Clinical adverse events (primarily dizziness, bradycardia, hypotension, and nausea) were significantly more common in the highest target concentration AZD7009 group vs placebo (P <.001). CONCLUSION: AZD7009 exhibited dose-dependent effects in converting AF to SR in AF patients and appeared to be associated with a low risk of proarrhythmia despite continued administration during a period of heightened vulnerability.     

Efficacy of encainide in supraventricular arrhythmias

This review summarizes the data from all the studies conducted in the United States and Europe that have evaluated the efficacy of encainide in patients with a variety of supraventricular arrhythmias. Using clinical criteria of efficacy, encainide was found to be effective or partially effective in 77% of patients evaluated by electrophysiologic means. Similar levels of efficacy were observed in patients with AV as well as AV nodal reentry arrhythmias. Patients with other forms of supraventricular arrhythmias in smaller series also experienced comparable degrees of efficacy. Encainide was discontinued because of intolerance by 8% of the patients in these studies: 6% because of side effects and 2% because of proarrhythmia.     

Should every patient with atrial fibrillation have the rhythm coverted to sinus rhythm?

Atrial Fibrillation is the most common atrial tachyarrhythmia. Consideration for the potential conversion of atrial fibrillation and the subsequent maintenance of sinus rhythm may be related to underlying pathology. Typically, extra cardiac factors such as thyroid hyperactivity help to determine initial therapy. Intrinsic cardiac factors may also influence the clinician's decision regarding potential cardioversion and maintenance of sinus rhythm. Some acute events such as pericarditis and the effects of cardiac trauma may resolve and result in spontaneous restoration of sinus rhythm. Other cardiac events such as acute myocardial infarction with with or without atrial ischemia, valvular disease, and others may result in the precipitation of atrial fibrillation. The major reasons to consider cardioversion, either medically or electrically, are ventricular rate control, hemodynamic improvement, sense of well being, and the avoidance of embolism. Certain clinical situations (e.g., Wolff-Parkinson-White syndrome) require urgent restoration of sinus rhythm in light of the potential for extremely rapid ventricular rates. It has been suggested that all antiarrhythmic drug administration should be initiated in the hospital setting, but the brief period of drug administration in an inpatient setting does not protect the patient from potential, late-onset proarrhythmic events. Both antiarrhythmic drug therapy and electric cardioversion are useful for restoration of sinus rhythm in both acute and chronic atrial fibrillation. The most important negative aspect of drug conversion of atrial fibrillation may be the potential development of a proarrthmic drug effect. Although controversial, conversion (medical or electrical) is probably indicated in every patient with the first episode of persistent atrial fibrillation, even if the patient is asymtomatic. The problem of recurrent atrial fibrillation requires clinical judgment relative to the frequency of episodes, the underlying disease(s) and the need for maintenance of a sinus mechanism.     

Celivarone for maintenance of sinus rhythm and conversion of atrial fibrillation/flutter

Celivarone in Atrial Fibrillation/Atrial Flutter. Introduction: Celivarone, a new noniodinated benzofuran derivative pharmacologically related to dronedarone and amiodarone, has been shown to have antiarrhythmic properties at a molecular level. The purpose of the 2 trials presented here (MAIA and CORYFEE) was to assess celivarone efficacy in the maintenance of sinus rhythm postcardioversion and for the conversion of atrial fibrillation (AF)/atrial flutter (AFL). Methods and Results: In the MAIA trial, 673 patients with AF/AFL recently converted to sinus rhythm were randomly assigned to receive 50, 100, 200, or 300 mg once‐daily dosing of celivarone; 200 mg daily of amiodarone preceded by a loading dose of 600 mg for 10 days; or placebo. At 3 months’ follow up, no significant difference was observed in time to AF/AFL relapse among the various celivarone groups and placebo. However, fewer symptomatic AF/AFL recurrences were observed in the lower‐dose celivarone groups (26.6% for celivarone 50 mg [P = 0.022] and 25.2% for celivarone 100 mg [P = 0.018] vs 40.5% for placebo at 90 days). Fewer adverse events were observed with the use of celivarone and placebo than amiodarone. In the CORYFEE study, 150 patients with AF/AFL were randomly assigned to once‐daily celivarone dosing of 300 or 600 mg, or placebo, for a 2‐day treatment period. There was no significant difference in the rate of spontaneous conversion to sinus rhythm between the treatment and control groups. Conclusions: In these studies, celivarone does not appear to be efficacious in the maintenance of sinus rhythm in AF/AFL patients or for the conversion of AF/AFL patients. (J Cardiovasc Electrophysiol, Vol. 23, pp. 462‐472, May 2012)     

Clinical significance of supraventricular tachyarrhythmias after acute myocardial infarction

160 survivors of acute myocardial infarction (AMI) were evaluatedto assess the clinical significance of supraventricular tachyarrhythmias(SVTA) occurring at discharge from the hospital after the acuteevent. the variables considered for the study were estimatedbefore hospital discharge; arrhythmias were quantified witha 24 h Hotter ECG monitoring system. SVTA occurred in 88 patients(55%). Single or repetitive supraventricular premature beatswere found in 65 (41%), paroxysmal atrial orjunctional tachycardiasin 20 (12%), bouts of atrial flutter or fibrillation in 3 (2%).Bivariate statistical analysis showed no relationship betweensex, previous cardiovascular history, type, and location ofAMI and SVTA occurrence. A close positive relationship was foundbetween age, left atrial dimension (LAD), cardio-thoracic ratio(CTR) and SVTA occurrence; an inverse relationship was foundfor left ventricular ejection fraction (LVEF). The presenceof SVTA appeared significantly related to age above 55 years,to LAD greater than 40 mm, to LVEF less than 45%, to serum creatinekinase peak levels over 1400 U l–¹ and to CTR over 0.49.Multivariate statistical analysis showed that five variablesare important in discriminating patients suffering from SVTA:age, LAD, LVEF, left ventricular fractional shortening, andCTR. SVTA occurring at discharge from hospital after AMI areindicative of impaired left ventricular pump function.     

Quantifying intracardiac organization of atrial arrhythmias using temporospatial phase of the electrocardiogram

INTRODUCTION: Separating nonisthmus-dependent atrial flutter (AFL) from "organized" atrial fibrillation (AF), or isthmus-dependent AFL, may be difficult using ECG characteristics alone. We hypothesized that temporal and spatial phase analysis of ECG atrial waveforms could effectively separate these rhythms by quantifying subtle variations in ECG atrial activation during supraventricular tachycardias (SVT). METHODS AND RESULTS: We studied 52 patients at electrophysiologic study (EPS) who demonstrated isthmus-dependent (n = 15) and nonisthmus-dependent (n = 9) AFL, atrial tachycardia (n = 6), AV nodal reentry (n = 9), orthodromic reciprocating tachycardia (n = 6), and AF (n = 7). Atrial activity was represented as a series of correlations of an atrial template to successive time samples of the arrhythmia ECG. Spatial phase was analyzed as a reproducible relationship of this atrial activity between leads over time; temporal regularity was measured from power spectra. Spatial phase was maintained (coherent) in lead planes V5/aVF (XY), V5/V1 (XZ), and aVF/V1 (YZ) in 15 of 15 cases of isthmus-dependent AFL, but in only 1 of 9 cases of nonisthmus-dependent AFL (P < 0.01; chi2). Temporally, all cases of AFL showed one dominant peak on correlation spectra (magnitude >6 dB), suggesting one activation wavefront, although this was smeared in nonisthmus-dependent cases. In contrast, AF showed inconsistent spatial phase in all planes and broad band spectra, consistent with multiple and/or variable activation paths. All other SVTs showed spatial coherence and one dominant spectral peak. CONCLUSION: Coherence of temporal and spatial phase is a powerful approach to measure the spatial organization of intracardiac activation from the ECG that reveals a spectrum from SVT to isthmus-dependent and nonisthmus-dependent AFL, to AF.     

Intravenous flecainide acetate for the clinical management of paroxysmal tachycardias

Intravenous flecainide acetate (2 mg/kg) was administered to 40 patients undergoing routine electrophysiological evaluation for the investigation of recurrent paroxysmal tachycardias. Ten patients had recurrent atrial flutter, 11 patients had recurrent atrial fibrillation, one of whom also had paroxysmal left atrial tachycardia, and 19 patients had recurrent ventricular tachyarrhythmias (17 with recurrent ventricular tachycardia and 2 with recurrent fascicular tachycardia). Flecainide was administered during tachycardia (over 5 to 10 minutes) to all patients with atrial flutter, to 10 patients with atrial fibrillation, and to 17 patients with ventricular tachyarrhythmias. In the remaining 3 patients with ill-sustained arrhythmias flecainide was administered during sinus rhythm and reinitiation of tachycardia was then attempted. Flecainide restored sinus rhythm in only 2 patients with atrial flutter (20%), in 9 patients with atrial fibrillation (90%), in 12 patients with ventricular tachycardia (80%), and in one of the 2 patients with fasicular tachycardia. Flecainide also successfully terminated the left atrial tachycardia. Two patients experienced proarrhythmic side effects during flecainide administration, one of whom required intervention by cardioversion. Minor dose effects included oral paresthesia, transient drowsiness or dizziness, and occasional visual blurring. Flecainide acetate is an effective antiarrhythmic agent for the acute termination of recent onset paroxysmal atrial and ventricular tachyarrhythmias.     

静脉注射地尔硫与毛花甙-C控制快速房性心律失常心室率即时疗效和安全性的对比观察

目的　观察和比较静脉注射地尔硫、毛花甙C控制快速心房颤动 (房颤 )和心房扑动(房扑 )心室率的即时疗效及安全性。方法　 5 4例快速房颤或房扑患者 ,采用随机方式分两组 ,分别静脉注射地尔硫、毛花甙C。结果　地尔硫、毛花甙C组控制房颤或房扑的快速心室率总有效率分别为 :94 %、70 % ,心室率平均下降幅度分别为 :3 4%、2 3 % ,平均起效时间分别为 :( 7 1± 4 2 )分钟、( 3 2 8± 2 2 8)分钟。地尔硫组出现可耐受性低血压 2例 ,发生窦性停搏 1例 ,均自行缓解 ,无心力衰竭加重表现。结论　静脉注射地尔硫能迅速、安全、有效地控制房颤、房扑的快速心室率。     

Mechanism of action of sotalol in supraventricular arrhythmias

Sotalol has a virtually unique antiarrhythmic profile in that it combines the properties of the Class II beta-blocking agents with the Class III properties that prolong repolarization. The Class II action exerts a marked effect on atrioventricular nodal conduction and makes sotalol a suitable drug for the treatment of adrenergic-induced supraventricular tachycradias. Sotalol helps to prevent or slow supraventricular arrhythmias involving the atrioventricular node as part of a reentrant pathway and also helps to control the ventricular rate during supraventricular arrhythmias conducted to the ventricles over the normal atrioventricular pathway. The capacity of conduction of accessory pathways is diminished by sotalol, thereby decreasing the ventricular rate during atrial fibrillation in the Wolff-Parkinson-White syndrome. The effects of sotalol on conduction of the cardiac impulse (Class I effects) have been probably overlooked and those on true refractoriness (Class III effects) overestimated.     

阵发性房颤自行转复的预测性

目的 发现预测房颤病人自行转复的相关因素,并初步探讨其临床意义.方法 采用Logistic回归分析法分析和比较1988年9月至1998年9月我院收治的192例发病时间＜72 h的房颤自行转复和非自行转复病人的临床特点和超声心动检查结果.结果 入院时房颤持续时间＜24 h的自行转复病人和非自行转复病人分别为118例(89.4%)和40例(66.7%).结论 房颤发作时间＜24 h是房颤自行转复的唯一预测指标.对自行转复可能性大的病人,可延缓使用转复心律的药物和直流电转复.     

Conversion of atrial fibrillation to sinus rhythm and rate control by digoxin in comparison to placebo

AIMS: A randomized, double-blind study with a high dose of digoxinadministered intravenously for conversion of atrial fibrillation(not due to haemodynamic alterations) to sinus rhythm, and forrate control in converters and nonconverters was set up. Outcomemeasures were conversion within 12 h; time to conversion; earlyrate control; and stable slowing within 12 h. METHODS: We studied 40 patients with recent onset (<1 week) atrialfibrillation; controls received saline intravenously, the otherpatients digoxin 1·25 mg. RESULTS: One patient converted before digoxin administration. Conversionoccurred in 9/19 patients on digoxin and in 8/20 on placebo(ns). The mean time to conversion tended to be shorter onlyfor digoxin. Two late conversions on placebo were observed within24 h. Heart rate during atrial fibrillation decreased after30 min for converters and non-converters (P<0·05).For all patients on digoxin, heart rate after 30 min was lowercompared to baseline (P<0·002) and to placebo (P<0·02).Persistent, stable slowing occurred only in 3/10 non-converterson digoxin (P<0·05), and two patients developed bradyarrhythmias.QTc was shortened immediately after conversion in all patients.Converters had baseline characteristics similar to those ofnon-converters. CONCLUSIONS: Intravenous digoxin offers no substantial advantages over placeboin recent onset atrial fibrillation with respect to conversion,and provides weak rate control.     

Value of flecainide in supraventricular arrhythmias

Flecainide acetate (Flecaine) is a new antiarrhythmic which has recently become available; its efficacity in treatment of ventricular rhythm disorders has been amply demonstrated. In this study we have evaluated its efficacity per os in treatment of auricular rhythm disorders refractory to the usual therapies, and its effects on the accessory routes of atrioventricular conduction. The results are very promising and better than those obtained with amiodarone in auricular disorders. They show that flecainide is a drug of importance among therapeutic agents used in treatment of auricular arrhythmia, and its action on Kent's bundle makes it a drug of choice in management of Wolff-Parkinson-White syndrome, especially as it seems equally efficacious in its action on the accessory routes with a short refractory period. Most of our patients did not present organic cardiopathy and the side-effects were generally benign. A non-negligible number of cases of paroxysmal hypertension were noted, in disagreement with literature data, and this point needs to be clarified by further study.     

Mechanisms underlying the development of atrial arrhythmias in heart failure

There is an important association between heart failure and the development of atrial arrhythmias. Although most often associated with atrial fibrillation, there is some evidence to suggest an association between heart failure and other atrial arrhythmias and, in particular, atrial flutter and atrial tachycardia. The mechanisms by which these common atrial arrhythmias may arise in patients with heart failure are discussed.     

Direct conversion of atrial flutter to sinus rhythm with low-output,short-duration transesophageal atrial pacing

Background and hypothesis: Transesophageal atrial pacing (TAP) is useful for terminating paroxysmal non-selfterminating atrial flutter (RAF); however, high output pacing of long stimulus duration causes severe symptoms such as chest pain. The objective of this study was to investigate the effect of low-output, short-duration TAP on the conversion of PAF. Methods: We applied low-output (within 15 mA with a pulse duration of 10 ms), short-duration (within 4 s) TAP in 31 patients (50±19 years) with PAF. Transesophageal pacing was delivered with 10 pulses of burst pacing at intervals that were 20 ms shorter than those of the flutter wave length. When the conversion was unsuccessful, we delivered 20 pulses of burst pacing. Results: Sixteen patients (52%) were converted directly to sinus rhythm and 12 (38%) to atrial fibrillation. Transesophageal pacing was ineffective in 3 (10%) patients. The duration of atrial flutter, maximum flutter wave amplitude, effective pacing intervals, underlying heart diseases, and cardiac function were not different between patients who had direct conversion to sinus rhythm and those converted to atrial fibrillation. The patients who had direct conversion to sinus rhythm had longer flutter wave cycle lengths than those converted to atrial fibrillation (248 vs. 221 ms, p<0.005). No patient had complications and complained of any symptoms. Conclusion: Low-output, short-duration TAP was useful to convert PAF directly to sinus rhythm without side effects.     

An approach to therapy of supraventricular tachyarrhythmias: An algorithm versus individualized therapy

Approaches to the treatment of supraventricular arrhythmias, including atrial fibrillation, atrial flutter, atrial tachycardia, atrioventricular (AV) reentrant tachycardia, and AV nodal reentrant tachycardia, continue to evolve. Within the past two decades, many new and effective treatments have become available. These include several new antiarrhythmic agents, ablative therapies, pacing and surgical modalities, and cardioversion/defibrillation techniques. This paper provides an algorithm for the treatment of these supraventricular arrhythmias which includes therapy for the acute episode as well as the prevention of subsequent episodes of the tachyarrhythmia.     

Propafenone versus procainamide for conversion of atrial fibrillation to sinus rhythm

Background and hypothesis: Antiarrhythmic drugs are widely used for treatment of atrial fibrillation (AF) and restoration off sinus rhythm. This prospective, randomized, and controlled study compared the efficiency and safety of propafenone versus procainamide for the treatment of acute AF. Methods: In all, 117 patients (55 women, 62 men, mean age 64.2 ± 13 years, median 63 years) who presented with AF were included in the study. Exclusion criteria were signs or symptoms of heart failure on physical examination, recent myocardial infarction or cardiac surgery, cardiogenic shock, or hypotension. Forty-one patients spontaneously recovered sinus rhythm; the remaining 76 patients were randomized to receive propafenone or procainamide. Propafenone was given at a dose of 2 mg/kg body weight intravenously (IV) over 30 min. Patients randomized to receive procainamide received a bolus of 100 mg IV administered every 5 min up to a maximum dose of 1 g. The clinical characteristics of the two groups were comparable. Results: The number of patients who recovered sinus rhythm after the treatment was larger in the procainamide-treated group (Group 1) (69.5%) than in the propafenone-treated group (Group 2) (48.7%); p < 0.05. The time required for cardioversion was significantly lower in Group 1 (mean 4.1 ± 1.3 h). than in Group 2 patients (mean 7.3 ± 2.6 h) (p<0.01). Conclusion: In the present study, procainamide was more effective than propafenone for the treatment of AF of short duration.     

Stable secondary arrhythmias late after intraoperative radiofrequency ablation of atrial fibrillation: incidence, mechanism, and treatment

INTRODUCTION: Intraoperative radiofrequency (RF) ablation is an effective treatment of atrial fibrillation (AF). However, secondary arrhythmias late after ablation may complicate the patient's course. We report on the incidence, mechanisms, and treatment of gap-related atrial flutter and other secondary arrhythmias during long-term follow-up. METHODS AND RESULTS: In 129 patients who underwent intraoperative RF ablation with placement of left atrial linear lesions using minimally invasive surgical techniques, secondary arrhythmias were analyzed during long-term follow-up (20 +/- 6 months). Transient atrial arrhythmias during the first 3 postoperative months were excluded. In 8 (6.2%) of 129 patients, sustained stable secondary arrhythmias were documented. Left atrial, gap-related atrial flutter was observed in 4 patients (3.1%). The flutter was treated by percutaneous RF ablation in 3 patients (2.3%) and with drugs in 1 patient (0.8%). In 2 patients (1.6%), right atrial isthmus-dependent atrial flutter occurred and was treated successfully by percutaneous RF ablation. In 2 patients (1.6%), ectopic right atrial tachycardias occurred and were treated with percutaneous RF ablation. CONCLUSION: Late after intraoperative RF ablation of atrial fibrillation, three types of stable secondary arrhythmias were observed in 6% of patients: left atrial gap-related atrial flutter, right atrial isthmus-dependent atrial flutter, and ectopic atrial tachycardia. Gaps after intraoperative RF ablation due to noncontinuous or nontransmural linear lesions may lead to stable left atrial macroreentrant tachycardias, requiring new interventional therapy.     

Azd7009: a new antiarrhythmic drug with predominant effects on the atria effectively terminates and prevents reinduction of atrial fibrillation and flutter in the sterile pericarditis model

INTRODUCTION: We tested the hypothesis that AZD7009 terminates induced atrial fibrillation (AF) and flutter (AFL) and prevents their reinduction, and that effects on refractoriness, conduction, and excitability are predominantly on the atria. METHODS AND RESULTS: Thirty-eight electrophysiologic studies were performed during AZD7009 infusion in 11 dogs with sterile pericarditis. The effects of AZD7009 on refractoriness, conduction, and capture threshold were studied and its antiarrhythmic efficacy tested. Simultaneous multisite biatrial mapping was performed in 7 dogs to assess arrhythmia termination. AZD7009 prolonged arrhythmia cycle length (CL) from 121 +/- 7.8 to 157 +/- 9.7 msec (P < 0.001) before terminating 23 of 23 AF/AFL episodes. Mapping demonstrated that AF/AFL CL prolonged and then terminated in area(s) of slow conduction in a reentrant circuit. Arrhythmia reinduction failed in 19 of 20 attempts. At 400-msec CL, atrial and ventricular refractoriness and QT interval increased 33%, 17% (P < 0.001 vs atrial refractoriness), and 9%, respectively. Atrial capture threshold increased in a CL-dependent manner: 1.8 +/- 0.3 to 2.2 +/- 0.3 mA (CL 400 msec); 2.1 +/- 0.3 to 2.8 +/- 0.5 mA (CL 300 msec), and 2.2 +/- 0.3 to 5.3 +/- 0.8 mA (CL 200 msec). Only minor nonsignificant changes occurred in the ventricles: 0.95 +/- 0.05 to 0.98 +/- 0.06 mA (CL 400 msec), and 1.14 +/- 0.12 to 1.16 +/- 0.13 mA (CL 333 msec). Atrial conduction time increased 8 +/- 1.4 msec (CL 400 msec), 8.3 +/- 1.5 msec (CL 300 msec), and 13.2 +/- 1.6 msec (CL 200 msec, all P < 0.001), but ventricular conduction time was unchanged. CONCLUSION: AZD7009 is highly efficacious in terminating AF/AFL and preventing reinduction in this model. It exhibits marked effects on atrial electrophysiology but has only modest effects on the ventricle.